Electrical wiring device



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Jan. 22, 1957 LAWRENCE 2,779,012

ELECTRICAL WIRING DEVICE Filed May 17, 1954 6 John J). Lawrence 38 INVENTOR.

United States Patent ELECTRICAL WIRING DEVICE John D. Lawrence, Trenton, N. J. Application May 17, 1954, Serial No. 430,061

16 Claims. (Cl. 339-269) This invention relates to electrical wiring devices, such as receptacles, switches, connectors and the like, which are adapted for optional side and back wirmg.

One of the principal objects of the present invention is to provide a wiring device in which the clamping nuts or elements are captive to the wire supporting member which carries the contact elements or formations.

In previous devices of the character mentioned provided with loose clamping nuts great \difiiculty has been experienced in the installation of the service wires because of the tendency of the nuts to move out of correct position to receive the wires, during their insertion.

Another, and important object of this invention is to provide a wiring device of the character mentioned in which the wire clamping means consists of a combined spring clamp and nut carried by the wire supporting member for securing either single or stranded wires in fixed position in the wiring fixture or housing.

A further object of the invention is to provide a wiring device of the character mentioned in which the combined spring clamp and nut are formed integrally with the wire supporting member.

Another object of the present invention is to provide a wiring device of the character mentioned in which the clamping screw can be used as a means of lifting the clamping element away from the wire supporting member to permit insertion and initial spring clamping of either a single or a stranded wire between the clamping element and the wire supporting member, and thus hold the wire against axial withdrawal from the device until the clamping screw can be tightened for permanently securing the wire against withdrawal.

Another object of the invention is to provide a wiring device of the character mentioned in which the clamping nut is reinforced by forming it in the shape of a cup with the edge of the rim engaging the wire.

A still further object of the present invention is to provide a wiring device of the character mentioned with positive mechanical gripping action in addition to an initial friction grip on the wire.

Other objects and advantages of the invention will be apparent from the following specification and the accompanying drawings forming a part thereof, in which Fig. 1 is a side elevation of one embodiment of my improved wiring device, with the plastic housing therefor shown in dotted lines;

Fig. 2 is a front elevation showing a pair of the devices illustrated in Fig. 1;

Fig. 3 is a rear view of the plastic casing showing the openings for back wiring of two sets of Wires;

Fig. 4 is an enlarged section taken on the line 44 of Fig. 1;

Fig. 5 is a fragmentary enlarged view showing a portion of a wiring device as viewed in Fig. 1;

Fig. 6 is a view of the Wiring device as viewed from the opposite side from Fig. 5;

Fig. 7 is a section taken on the line 7--7 of Fig. 6;

Fig. 8 is a section taken on the line 8-8 of Fig. 5;

Fig. 9 is a section taken on the line 99 of Fig. 6;

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Fig. 10 is a sectional view similar to Fig. 8, but showing a modified form of the invention; and

Fig. 11 is :a sectional view similar to Fig. 7 but showing a further modified form of the invention.

Referring to the drawings in which like numerals designate like parts or elements in the several views, my invention is illustrated in connection with one type of electrical wiring fixture 10, this being a double receptacle for detachable plugs of the usual type (not shown). In Figs. 1 and 2 the fixture 10 is shown only in dotted lines. It should be understood that my invention is equally well applicable to various other types of electrical wiring fixtures, including single receptacles, switches and connectors.

In general, my invention is limited to the metal connections of the wiring fixture including the usual type of wire supporting member 12 which is provided at each end in a double fixture, and at one end in a single fixture, with electrical contact elements 14 for reception of complementary contact elements (not shown) of the detachable plugs already'mentioned. In previous devices of the type mentioned the electric service wires have been connected to the member 12 by means of loose clamping nuts and screws, each nut usually having therein a shallow groove facing the flat surface of the member 12 to receive the end portion of a wire inserted from the back or rear of the fixture and extending transversely across the member 12, between the nut and the wire supporting surface of the member 12. Such arrangements have several objectionable features which cause difficulty and loss of time in the installation of service wires. For example, the loose nut has a tendency to rotate to an angular position out of alignment with the wire; the nut frequently falls against the member 12 and blocks the entrance of the wire between the nut and member 12; and after the wire is inserted it may accidentally be partially withdrawn before the screw can be tightened. There are other typesof fixtures in which separate devices are provided for initially clamping the wires when inserted, but such fixtures of that type of-which I am aware are of excessively complicated and expensive construction in WhlCh'it is difficult to insert a wire into clamped position, and in which it is also difficult or impossible to withdraw the wire after it is inserted into the fixture.

All the disadvantages mentioned are effectively overcome in my improved wiring device by means of very simple and inexpensive construction which will now be described.

In a double wiring device according to my invention, as illustrated in Figs. 1, 2 and 3, each of the wire supporting members 12 has rigidly connected thereto a spring clamping arm 16 in lieu of the usual loose clamping nut. The arm 16 is free at one end for movement from and toward the supporting member 12 and is provided toward its other end with a through threaded opening 18. The supporting member 12 is also provided with a through opening 20 in concentric relation with each of the threaded openings 18. A clamping screw 22 having a relatively large .head 24 projects loosely through the opening 20 which is of substantially greater diameter than that of the screw and the threaded opening therefor in the spring clamping arm 15. In the form of the invention illustrated in Figs. 1 to 9 the clamping arm 16 is formed'integrally with the wire supporting member 12, which is made of flat resilient metal. The arm 16 is of cup formation with the free edge of its rim portion 26 facing the wire supporting surface of the member 12. The cup-shaped arm may be of oblong plain formation in longitudinal alignment with the edges of the member 12, and of less width than the member 10. Longitudinal edge 28 of the arm 16 may be offset from theadjacent edge. of the member 12, and at that side connected to the edge of the member 12 by an integral web portion 30 which is bent inwardly in overlapping relation with the wire supporting surface of the member 12 and rigidly'supports the arm 16 also in overlapping relation with the wire supporting surface of the member 12. The free edge 32 of the rim 26 transversely opposite the web portion 30 is substantially in perpendicular alignment with the edge of the member 12 on. that side to engage the forward end portion of a wire 34 which is inserted from the opposite side transversely across the member 12.

In the embodiments of the invention illustrated, the edge 32 of the rim 26 is normally spaced from the wire supporting surface of the member 12 a less distance than the diameter of a wire of the least diameter for which the device is designed, so that it is necessary to liit'the free end 36 of the arm 16 before a wire 34 can be inserted between it and the supporting member 12. This is effected by partially backing out the clamping screw 22, as indicated in dotted lines in Fig. 8, and pressing inwardly on the head 2e of the screw, the head 24 being accessible outside the fixture 10. This lifts the free end of the arm to permit insertion of the wire. When the screw is released the spring tension exerted through the web portion 30 will cause the edge 32 of the arm 16 to engage and initially grip the Wire 34 between the rim and the member 12. The screw 22 may then be set up until the head 24 forces the arm and supporting member tightly against the wire, thus completing the permanent installation. When it is desired to withdraw the wire from the fixture ill it is necessary only to partially back out the screw 22, press the head inwardly, thereby lifting the free end of the arm 16, and withdraw the wire. If desired, in order to provide for greater initial spring gripping power against the wire, the arm 16 may be tensioned in a manner whereby the wire engaging surface will normally be in contact with the supporting member 12. The opening in the supporting member 12 is of sufficient diameter to permit free angular movement of the screw 22 to accommodate wires of various diameters. The edge 36 of the rim 26 is normally spaced from the wire supporting surface of the member 12 a greater distance than the diameter of a wire of the greatest diameter for which the device is designed, thus accommodating not only wires of small diameter but also various larger diameters. An advantage of this arrangement in the installation of the larger wires is that by means of the screw 22 both the edges 32 and 36 can be pressed into tight clamping engagement with the wire. With wires of any size the installation requires only the lifting of the clamping arm 16 by means of the screw 22, inserting a wire 34 from the rear of the fitting 1i? through openings 38 (shown dotted in Fig. l) and transversely across the member 12 until the forward end is stopped by the wall 40 (Fig. 4) in the fitting Ill; and then tightening up the screw 22.

A notch is formed in the forward edge of the supporting member 12 in substantial perpendicular alignment with the wire 34 and opposite the rim edge 32, and with. the corner 44 of the edge of the notch adjacent the end portion of the wire relatively sharp, as illustrated in Fig. 9, so that it will-bite into the wire. When pressure is applied against the wire by the rim edge 32, through the screw 22, the Wire will be slightly bent over the edge of the notch, which is of greater width than the diameter of the wire, as indicated in dotted lines in Fig. 9, thereby forming a mechanical lock joint against withdrawal of the wire from its permanent installation. This notch also provides means for visual inspection of the ends of the wire after it is secured in final position, as will be seen in Figs. 1 and 2.

Although my improved wiring device has been described in connection with installations known in the trade as back wiring, it is also suitable for side wiring, in which the ends of the wires are coiled about the screw 22 between the head 24 and the member 12 and the screws tightened. No change in the design is required for this type of installation.

The device has also been described as having the clamping arm formed integrally with the member 12. However, if desired, in order to use a relatively soft metal supporting member and a clamping arm of a harder material than that of the wire, the clamping arm 16a may be formed separately with the spring web portion 300 as illustrated in Fig. 10 and secured to the supporting member 12 by means of rivets 46 or other suitable means. In this form of the invention the clamping arm could, for example, be made of steel and the member 12 from non-ferrous metal.

Although the cup-shaped clamping arm has a number of advantages, such as great strength and narrow edge grip of the wire, it is within the scope of my invention t3 form the clamping arm without the cupped portion as shown in Fig. 11 in which the clamping arm 48 is formed relatively flat and attached at one end to the member 12 by means of rivets 50 or other suitable means. in this design the free end of the arm may be provided with an arched portion 52 or other suitable formation for the engagement of wires of various diameters. The same general type of screw 22 is used with this clamp.

in Fig. 7 it will be observed that the free end 54 of the cup-shaped arm projects toward the Wire supporting surface beyond the plane of the wire contacting edge 32. The purpose of this projection is to guard the wire against lateral movement beyond the end of the clamping arm. A boss 56 may be formed about the screw opening 18 to provide a greater number of threads.

Although my invention has been described as a double Wiring device it is equally well adapted to single Wiring devices. For example if a member 12 is cut transversely along the line A-A, as indicated in Fig. 5 the portion carrying the arm 16 would be single.

Obviously various changes in the construction of my improved wiring device may be made without departing from the spirit of my invention. Therefore, it should be understood that the embodiments of my invention shown and described are intended to be illustrative only and limited only within the appended claims.

I claim:

1. An electrical wiring device comprising, in combination, a metal Wire supporting member having an opening therethrough and provided at one end thereof with electrical contact means, a resilient metal clamping arm rigidly connected at one end thereof to said supporting member in overlapping relation therewith and with the other end of said clamping arm free for movement from and toward said supporting member, said clamping arm having therein a through threaded opening of a lesser diameter than that of the opening in said supporting member and in concentric relation therewith; and a headed clamping screw projecting through the opening in said supporting member and the threaded opening in said clamping arm, the free end of said clamping arm being liftable away from said supporting member by means of said screw to permit a Wire to be inserted transversely across said supporting member between said member and said clamping arm.

2. An electrical wiring device comprising, in combination, a metal wire supporting member having an opening therethrough and provided at one end thereof with electrical contact means, a resilient metal clamping arm rigidly connected at one end thereof to one edge of said supporting member in overlapping relation therewith and with the other end of said clamping arm free for move ment from and toward said supporting member, said clamping arm having therein a through threaded opening of a lesser diameter than that of the opening in said supporting member and in concentric relation therewith; and a headed clamping screw projecting through the opening in said supporting member and the threaded opening in said clamping arm, the free end of said clamping arm in, J

being liftable away from said supporting member by means of said screw to permit the initial spring clamping of a wire extending transversely across said supporting member between said member and said clamping arm.

3. An electrical wiring device comprising, in combination, a metal wire supporting member having an opening therethrough and provided at one end thereof with electrical contact means, a resilient metal clamping arm overlapping said supporting member, said clamping arm having at one end a lateral resilient web portion rigidly connected to one edge of said supporting member and at its other end a wire engaging portion extending freely beyond the edge of said web portion longitudinally of said supporting member, said clamping arm having therein a through threaded opening of a lesser diameter than that of the opening in said supporting member and in concentric relation therewith; and a headed clamping screw projecting through the opening in said supporting member and the threaded opening in said clamping arm, the free end of said clamping arm being liftable away from said supporting member by means of said screw to permit the initial spring clamping of a wire extending transversely across said supporting member between said member and said clamping arm.

4. An electrical wiring device according to claim 3 in which the clamping arm is normally spaced from the supporting member.

5. An electrical wiring device according to claim 3 in which the edge of the supporting member adjacent the end of the wire is provided with a notch in axial alignment with the wire to efiect a bend in the wire over the front edge of said notch under pressure from said clamping arm.

6. An electrical wiring device according to claim 3 in which the outer end of the free portion of said clamping arm is extended toward the supporting member to limit outward lateral movement of the wire on the surfaces of said supporting member and said clamping arm.

7. An electrical wiring device comprising, in combination, a metal wire supporting member having an opening therethrough and provided at one end thereof with electrical contact means, a resilient metal clamping arm overlapping said supporting member, said clamping arm being formed with a perpendicular rim surrounding its outer edge and projecting toward said supporting member, said clamping arm having at one end a lateral resilient web portion rigidly connected to one edge of said supporting member and at its other end a wire engaging portion extending freely beyond the edge of said web portion longitudinally of said supporting member, said clamping arm having therein a through threaded opening of a lesser diameter than that of the opening in said supporting member and in concentric relation therewith; and a headed clamping screw projecting through the opening in said supporting member and the threaded opening in said clamping arm, the free end of said clamping arm being liftable away from said supporting member by means of said screw to permit the initial spring clamping of a wire extending transversely across said supporting member between said member and the rim of said clamping arm.

8. An electrical wiring device according to claim 7 in which the clamping arm is normally spaced from the opposed surface of said supporting member.

9. An electrical wiring device according to claim 7 in which the edge of the supporting member adjacent the forward end of the wire is provided with a notch opposite the wire and the rim of said clamping arm, and in axial alignment with said wire, to efiect a bend in the wire over the frontal edge of said notch under the pressure of said rim in cooperation with said clamping screw.

10. An electrical wiring device according to claim 7 in which the outer end of the free portion of the rim of said clamping arm is extended toward the supporting member to limit outward lateral movement of the wire on the surfaces of said supporting member and said clamping arm.

11. An electrical wiring device according to claim 7 in which the portion of the rim opposite the forward end of the wire is longer than the transversely opposite portion to permit the insertion between said supporting memher and said clamping arm of wires of various diameters.

12. An electrical wiring device according to claim 7 in which the clamping arm and resilient web are formed integrally with the supporting member.

13. An electrical wiring device according to claim 7 in which a boss surrounding the threaded opening in the clamping arm is formed integrally with said arm outwardly thereof.

14. An electrical wiring device according to claim 7 in which the clamping arm and resilient web are formed integrally with the supporting member, and in which said clamping arm is of lesser width than that of said supporting member, but also in which the forward edge of the rim is in perpendicularly opposed relation to the outer end of the notch in said supporting member.

15. An electrical wiring device according to claim 7 in which the perpendicular Wire engaging rim of the clamping arm is of greater length at the edge which engages the end portion of the wire than the opposite, or entrance portion of said rim, to permit the entrance of wires of relatively large diameters.

16. An electrical wiring device according to claim 9 in which the inner edge of said notch is provided with a relatively sharp corner opposed the side of said wire.

References Cited in the file of this patent UNITED STATES PATENTS 1,904,919 Hartwig Apr. 18, 1933 2,216,740 Hubbell Oct. 8, 1940 2,315,523 Hubbell Apr. 6, 1943 2,317,382 Hubbell Apr. 27, 1943 2,532,625 Kieser Dec. 5, 1950 

